1. Field of the Invention
This invention relates to alkylating syntheses and gasoline additives in general. This invention also relates to the favorable production of alkylcyclopentadienes with minimal production of di- and polyalkylated cyclopentadiene by-products.
2. Description of the Prior Art
Methylcyclopentadiene manganese tricarbonyl (MMT) is a valuable additive for leaded gasoline and may find use in other fuels. The use of other alkyl homologs of MMT in fuels is also indicated.
The successful production of MMT depends upon a reliable source of methylcyclopentadiene unmixed with higher alkylated by-products. The methylcyclopentadiene starting material has been available in suitable purity by obtaining it from a petroleum cracking process where undesirable portions of the di- or polyalkylated cyclopentadienes are not formed. However, the amount of methylcyclopentadiene available is limited to a single source and an alternative source is desirable.
Both McLean et al, Tetrahedron, 21, 2313 (1965) and Mironov et al, Tetrahedron, 19, 1939 (1963) report the synthesis of methylcyclopentadiene with the attendant production of large portions of di- and polymethylated cyclopentadienes. Synthesis may form dimethyl-, trimethyl-, or even tetramethylcyclopentadiene. The higher alkylated cyclopentadienes are present in an amount of about 10 mole percent or more which is unacceptable for two reasons. The dimethylcyclopentadiene is separated from the methylcyclopentadiene product only by means of a difficult distillation. Also, the higher alkylated cyclopentadienes interfere with the production of MMT.